This invention relates to an ultrasound system and method for obtaining ultrasound data with an array of transducer elements. In particular, the transducer elements are spaced to create a sparse ultrasonic phased array.
Ultrasound systems include a beamformer and an image processor. The beamformer generates transmit waveforms and coherently sums reflected receive signals. The beamformer also filters the information. The filtering may be selectable between a harmonic and a fundamental frequency. For example, the filter isolates information associated with a second harmonic frequency of a fundamental transmit frequency. The coherently summed information is processed by the image processor to generate an image on a display.
The transmit waveforms from the beamformer are converted to acoustical energy, and the reflected acoustical energy is converted into receive signals by an array of transducer elements. In order to avoid grating lobes in steered transducer arrays, the distance from the center of a transducer element to the center of adjacent transducer elements is maintained at around one-half a wavelength of a transmit and receive center frequency. In non-steered arrays, this distance is on the order of one wavelength. Increasing the lateral resolution by using a larger transducer extent in the lateral dimension would require a greater number of transducer elements. However, increasing the number of elements increases the cost and complexity of the transducer and the associated beamformer. For example, the number of beamformer transmit and receive channels is increased.